A simple and user-friendly protocol for chitosan nanoparticle synthesis

Despite the widespread use of chitosan nanoparticles (CNPs), a simple, cost-effective, and reproducible synthesis protocol remains a critical unmet need. Existing protocols for ionic gelation methods are often laborious, requiring overnight stirring, costly filtration, and time-consuming lyophilization. In this study, we present a novel, easy-to-adopt, cost-effective, scalable, and highly reproducible protocol for synthesizing CNPs via ionic gelation, bypassing these common drawbacks. Our method standardizes the use of low molecular weight chitosan (0.1%) stabilized with Tween 80 in 1% acetic acid solution, crosslinked with sodium tripolyphosphate (STPP) in 3:1 volume ratio to form CNPs. The CNPs are efficiently separated using simple centrifugation, eliminating the need for complex and expensive lyophilization. The nanoparticles obtained were systematically characterized for their physicochemical and structural properties, including particle size, zeta potential, polydispersity index, morphology, functional groups, crystallinity, and elemental composition, using a wide range of analytical techniques such as UV-Vis spectroscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Energy-Dispersive X-ray Analysis (EDAX), Atomic Force Microscopy (AFM), and High-Resolution Transmission Electron Microscopy (HRTEM). Comprehensive characterization of synthesized CNPs consistently demonstrated the formation of well-defined, spherical amorphous nanoparticles within the nanometer range, exhibiting a positive surface charge, presence of functional groups, and desirable elemental composition. The protocol's simplicity, low cost, scalability, accessibility, and reproducibility of the synthesized CNPs make it a significant advancement for researchers in various fields. Given their inherent biocompatibility and functional versatility, these CNPs are highly promising for a wide range of applications, including antimicrobial coatings, food preservation, water treatment, drug delivery, and sustainable agriculture.